In present day technology, images are received and stored in various formats. On the reception end, the image can be input either through a scanner or through a frame grabber that is operable to receive a video input from a video camera, for example, and then digitize the image for storage thereof. Each of these input devices provides a predetermined format for the stored image. For example, the scanner has a predefined scanning head that determines the maximum resolution of the image. A relatively high resolution scanner may allow for 300 dots per inch (DPI) or more along the horizontal axis, each dot representing either a dark pixel (picture element) or a white pixel. This image is then stored as an image file with one of a predetermined number of image file formats. With respect to the frame grabber, this typically samples the incoming video on a given horizontal scan line, there being a predetermined number of horizontal scan lines per frame, and then dividing up the analog input value into "samples" or pixels that each have a digitized value of eight bits, representing the analog value. The image is then stored as a digitized frame in a frame buffer.
When an image is to be output, it is necessary to ensure that the stored image can be "mapped" to the output space of the output device. For example, if a scanner scanned at a resolution of 300 DPI and this were to be output on a laser printer at a resolution of, for example, 300 DPI, this would be a relatively easy task. However, if the resolution of the stored image were not equal to that of the output device, some adjustment would be required to map the full image to the full output space. One place this presents a problem is with respect to a received facsimile image, which typically has a resolution of 200 DPI. This would therefore require that each pixel be expanded to represent 11/2 pixels on the output. However, if the output device were a facsimile image, this would require a 300 DPI stored image to be translated to a 200 DPI FAX image. Typically, the image is merely reduced by a factor of two such that it is 150 DPI and then transmitted such that it only occupies 3/4 of a horizontal line in order to alleviate the need for translating pixels.
In order to convert a scanned image from either a scanner or a video source into pixels, it is necessary to perform various image enhancements. Since the input values from either a scanner or a video source are analog values, it is necessary to convert them to "gray-scales" in order to represent them with pixels that are either black or white. For example, a gray area would be represented by alternating black and white pixels. If the tone were decreased to a much grayer level approaching white, the number of white pixels would dominate the number of black pixels. This, of course, would be the reverse for a relatively dark gray area, wherein the black pixels would dominate over the white pixels. Since the eye cannot decipher individual pixels, it "averages the pixels". One area that has not been addressed for present technology is the receipt of a video image and subsequent retransmission of that image by facsimile. The difficulty that arises with this type of transmission is the incompatibility between the two formats. As described above, a facsimile typically operates at 200 DPI in a binary output space, wherein a typical video image is captured in an analog input space by a frame grabber and digitized with a resolution of 432 pixels across and 488 pixels along the vertical. The problem exists wherein it is necessary to map each pixel in the video image into black or white pixels in a facsimile transmission, and this mapping function controlled such that it covers the entire image or entire output space.